Blowpipe



April 15, 1941. w. J. JAcoBssoN :E1-m. 2,238,476

BLOWPIPEl F4195 oct. 20, 1937 Iliff/flug@ INVE'NTORS WILGOT J. JACOBSSONSAMUEL R. OLDHAM ATTORNEY Patented Apr.15,1941

Wilgot J. Jacobsson,

Qldham, Elizabeth, N.. Acetylene Company,

Virginia Scotch Plains, and '"'amuel R. J., asslgnors o Oxweld ia.corporation of West Application october zo, 1937, serial No. 169,930 v(c1. 15s-e214) 3 Claims.

blowpipe attachblowpipe attach- This inventio'n relates to a ment, andmore particularly a ment which is adapted to use eitherlow or mediu'mpressure fuel gas. The invention is especially useful asan attachmentfor existing blowpipes, notably for converting a conventional weldingblowpipe into a cutting blowpipe, to which use, however, it isnotlimited. Some of the features of the invention may be types ofblowpipes.

Fuel ,gas (as acetylene) may be available at different places or atdiierent times as low pressure (say less than 1 lb. per square inch) gasor as medium pressurey (say 15 lbs. per square inch) gas. As a matter ofeconomy-and convenience,

therefore, it is desirable for a user to have availutilized in other.

able asingle blowpipe which may be used eiciently with iuel gas at thesediierent pressures.

In the past, it has been customary to design blowpipes so that theywould not flashback at a given fuel gas pressure. However, increasing ordecreasing the.pressure to any considerable extent I alter the flashbackresistance of may materially For this reason, it has not been `theblowpipe.

possible to sure and medium pressure fuel gas, unless mixers or otherparts of the blowpipe were changed. Also, when both welding and cuttingwork is to be carried on in a shop, it is customary' to employ separate'welding and cutting blowpipes for the 5 respective operations and tokeep both blowpipes available in the shop. This practicetends further tomultiply the required number of blowpipes and the expense of blowpipeequipment.

One object of the invention is, therefore, to provide a blowpipe whichmay be used as acutting attachment 'and connected to a welding blowpipe,thereby saving the expense of purchasing and maintaining a completewelding blowpipe and also a complete cutting blowpipe for performing thetwooperations. Another vobject is to provide a single blowpipe which maybe used use the same blowpipe for low presbend at lthe front thereof andtwo Fig. 2 is across-section taken on the line II--II of Fig. 1;

Fig. 3 is a cross-section taken on the line III-III of Fig. 1;

Fig. 4 is a cross-section IV-lV of Fig. 1;`and A Fig. 5 is a broken-longitudinal mid-section showing the connection between the rear end ofthe attachment and the 'forward end of a'welding blowpipe handle.

vIn accordance with 4taken on lthe line the invention thereis provided ablowpipe comprising a body member, al

combustible gas mixture conduit, means providing anelongated cavityterminating at its forward end at the rear end of the mixture conduit,and terminating at its rear end in the body member, and means at theforward end of the blowpipe for discharging a combustible gas mixture.An elongated combustion-supporting gas conduit in the. cavity is spacedfrom the internal cavity wall to provide an elongated annular chamberhaving an appreciable Volume. A mixer nozzle in the cavity issecured tothe forward end of the combustion-supporting gas conduit and is vsoconstructed and arranged that backfires will pass intothe annularchamber. A generally U-shaped fuel-gas passage having an appreciablevolume and being adapted to contain `a large volume of f' fuel gas forreceiving and extinguishing backres,

which is disposed between the body member and the forward end of theblowpipe, has a, return y terminals at the rear thereof in the bodymember. A passage in the body member communicates between one of thevterminals of the .U-shapedfpassage and the annular' chamber. Suitablemeans are provided for, supplying fuel gas and combustionsupporting gas,respectively, to the other terminal of the U-shaped passage and tothecombusefficiently over a wide-range of fuel gas pressures.

A further object is the provision of such'a ,blow- `pipe which will besubstantially freeafrom flash-' entirefrange of operating.`

back action over its pressures.

- -ing the mixer-nozzle,

The above and other objects andnovel features of the invention will beapparent from the following description taken with the. accompanyingdrawing. inwhich: I

. AFigthrough a blowpipe comprising a'. cutting attachment,constructed-inaccordance with the invention;

1 is a broken longitudinal mid-section'v acetylene Ation-supporting gasconduit. The U-shaped fuelgas passage and the annular chamber cooperateto contain together a sufliciently large volume of fuel gas to receiveand extinguish backfires passthereby preventing flashbacks'. Forconvenience, the words -"4oxyge'n and will be used in this specificationto denote respectively any appropriate cutting and combustion-supportinggas,'and any appropriate fuel gas. J

A device constructed in accordance with the invention comprises a body Band a head H connected-by conduits generally, designated as C. The headH carries the blowpipe tip T at the forward end of the blowpipe which isconnected thereto by an'attachingnut N in the usual manner. The body Bhas gas passages therethrough connecting with the conduits C, andcontains the gas control elements of the blowpipe, as the valves and themixer. In the embodiment which is illustrated in the drawing, theblowpipe is constructed as a cutting attachment, and connecting means Jare provided for joining the blowpipe to a welding blowpipe handle A.

Q The handle A which is illustrated in the draw! ing (see Fig. 5) is awell-known form of welding blowpipe handle from which the mixer and stemhave been removed, and to which the connecting means J may be applied toattach the body B thereto. The handle A comprises the 'usual hollowshell I0, which is attached at its forward end to a forward block I I.The frontend of the forward vblock- IIv 'is formed as an externallythreads 34 on 'the forward end of the former connects the forward end ofthe oxygen conduit with the rear center portion of the cavity I3, and asecond passage `I1 connects the forward end of the acetylene conduiteccentrically with the rearv end of the cavity I3.

',I'he connecting means J by which the body B is connected to the handleA, comprises a nipple I8, having an external annular shoulder I9 formedthereon near its rear end. An axial passage 20 extends through thenipple I8,.and is carried rearwardly beyond the rest of the nipple by a,projection 2|, and is carried forwardly of the rest of the 'nipple b y aprojection 22 (see Fig. 1). A conical seat 23 is provided on the nippleat the end of the projection -2I, and a conical seat 24 is provided atthe end of the projection 22, for a' purpose which will later appear. Aplurality of longitudinal'passages 25 extend through the nipple I8eccentric tc, and in a direction sub# stantially 'parallel to that ofthe axial passage 20; and a conical seating surface 26 is providedtoward the rear end of the nipple I8 surrounding the ends of thelongitudinal passages 25.

A hollow nut 21,' having an internal shoulder 28 at its rear end, isformed to t over the nipple I8 with its internal shoulder in contactwith the external shoulder I9 o'n the fnipple. When the hollow nut 21 isin place on the nipple i8 with its shoulder 23l in 'contact with' theshoulder I9 of the nipple, it extends rearwardly beyond the projection2i, thereby protecting the seat 23 thereon. A retaining ring 23 isresiliently held in a groove 30 in the nipple immediately ahead of thehollow Anut 21 and maintains the latter in the-position which has -lustbeen described.

When th'e hollow nut 21 is 'screwed upon theI externally vthreadednipple end I2 of the forward block I i, the "conical seats 23 and 25 onthe nipple I3 seat in gas-tight contact with corresponding surfaces. and32-respectively, in the cavityl3 4of the forward block II. Thus, theaxial passage 2l through the nipple extends in gas-tight continuation ofthe oxygen passage I3 in the'forward block II and the plurality of'eccentric passages 2l through the nipple extend in continuation of .anannular chamberv 33 Awhich is formed in the cavity l: when ciosed by thenipple la 'with the extension 2|. extending therethrough.

.illustrated is that which surface 36 surrounds the end of an oxygenduct 31 which extends forwardly of the recess in the body B. f Theforward projection 22 on the nipple IB extends through the recess beyondthe rest of the nipple, thus forming with the walls of the recess 35anannular chamber 38 into which the plurality of eccentric passages 25lead,

The nipple I3 is'-. preferably made of sturdy construction with heavytubular walls on the extensions 2I and 22, in order to provide broadseats 23 and 24 thereon. Thus, when the nipple is attached, the seats 23and 24 come against the corresponding seats 3I and 36 with a definite,sure stop which makes gas-tight assembly certain. Attachment between thenipple and the body B is preferably made permanent. Accordingly, inattaching the nipple I8 to the body B, the threads 34 at the forward endof the nipple and the seat 24 may 'rst betinned, and the nipple is thensweated into the body B.

It is further preferred to form the body B of pressure-forged metalinstead of a casting, in

'I'he body B has a large oxygen valve chamber' 39 therein into which theoxygen duct 31 extends from the forward end of the axial passage 20 inthe nipple .I 8. Any known or convenient highcapacity valve mechanismmay be used to control the passage of cutting oxygen through the l valvechamber 39 to a discharge duct 4U formed in the. body B. I'he valvemechanism 4I here is described in our Patent No'. 2,213,043 forBlowpipe, issued August 27, 1940, and is operated by a lever 42 pivoted,as at 43, to the body B, also as described in our aforesaid patentapplication. Other forms of valve mechanism and other operating meansmight be employed. A cutting oxygen conduit 44 has one end fitted intothe body B at the forward end of the discharge duct 4l, and extends tothe l blowpipe head H, into which its forward end is tted A cuttingoxygen passage," extends forwardly in the head to the rear centerportion of the cavity 4,3 therein in which the tip T is held by theattaching n ut N. y

The mixer which is employed to form a combustible mixture 'of acetyleneand combustionsupporting oxygen is Asomewhat similar to that which visdescribed 2,198,341 of Wilgot J. Jacobsson, one 'of the in- Blowpipe,"issued April 23, 1940. This mixer vis formed by disposing a speciallyformed mixing assembly in an elongated cavity inthe body B, in a mannerwhich will-.now be explained. A bore 41 extends through the body B,oifset from,'and substantially parallel to the axis of the recess utherein. The cavity thus i formed continues forwardly through a tube orlarge conduit which islas-tightly connected to the body B, as bysilver-soldering at 4l. The

and claimed' in Patentv elongated cavity. It comprises a mixing elementor mixer nozzle 53, an elongated conduit 54, and a rear block 55', allrigidly connected together in coaxial series alignment and removablydisposed in the lelongated cavity. A passage 56 extends substantiallyaxially through the mixingv element 53, and a passage 51 extendssubstantially axially through the rear block 55, each passage being acontinuation of the passage through the elongated conduit 54. An annularshoulder 58, formed on the rear block 55 adjacent lits forward end,contacts an internal shoulder 59 of the bore 41 and thereby limits theaxial position of the unitary assembly within the elongated cavity, andalso positions the mixing element 53 axially of the elongated cavity.Contact between the annular shoulders 58 and 59 also seals thecontinuouspassage through the' mixing assembly from the annular passage or.chamber between the lelongated conduit 54 and the elongated cavityahead of the rear block 55 and prevents passage of gas from theelongated cavity on one side of the rear block to the other, exceptthrough the passage 51. The rear block 55 is internally threaded inorder that an instrument may be inserted therein for withdrawing theV'unitary assembly from the elongated cavity. An ordinary long machinescrew will serve for this purpose.

The mixing element 53 which is illustrated in the drawings issubstantially cylindrical in form and its forward end is a 4plane face60 transverse to the axis of the element, and preferably stands atsubstantially right angles to this axis. The length of the mixingassembly is such that when 'the annular shoulder 58 on the rear bl'ock55 contacts the internal shoulder 59 of the bore 41 the plane face 60 atthe forward end of the mixer is closely juxtaposed to, but slightlyspaced from, the face 52 at the rear end of the mixture conduit. Thus, anarrow gap 6I is formed between the two faces. The passage 58 throughthe mixingelement 53 is shown as being constricted-at its forwardend,-as as 62, in order to provide a metering orifice land to giveincreased velocity to the gaspassing through the mixing assembly as themixing elementcontact the inner wall of the elongated cavity and spacethe mixing element therefrom to provide a'passage around the mixingelement. The 'gap 6I and the passage along the outside of the mixinge1ement53 are of sunlcient size to permit the passage of backres. As thediameter of the rear block 55 is so chosen that the block ts exactlywithin the bore 41, the mixthe conduit 54 and along the outside of themix- 'and at right angles thereto.

41 and closes the end of the bore beyond the locking screw 64.

Combustion-supporting oxygen is carried from the passage 31 to the axialpassage through the mixingassembly by means of a duct 68 opening intothe passage 31, a valve chamber 69 at the far end of the duct 68, asecond duct 10 leading from the valve chamber 63 to an annular groove.

1I in the rear block 55, and a radial passage 12 extending from theannular groove 1I through the rear block 55V to the axial passage 51therein. A valve 13 in the valve chamber 69, operated by a valve wheel14, controls th'ev passage of combustion-supporting oxygen to the mixingassembly. i A vAcetylene flows throughthe eccentric passages 25 in thenipple I8 into the annular chamber 38,'

whence it passes through a bore 15 in the body B to the rear end of apassage 16 extending forwardly through the body B. One of the conduits11 of the group generally designated as C has its rear endterminating atand fitted into the body B at the forward end of the passage 16. Theconduit 11 is connected at its forward end toI the head H where a crossbore or header 18 connects its forward endl to the end of a secondconduit 18 which extends substantially parallel to the conduit 11 andhas its rear end terminating at and fitted into the body B. The conduits11 and'19 and the header 18 thus provide a generally U- Ishaped passage,disposed between the body member B andthe forward end of the blowpipe,having a return bend at the front and having two terminals at the rearin -the body member. A passage 80 in the body B extends substantiallyparallel to the passage 16 from the rear end of the conduit 18 and isintersected by a cross passage 8| which opens into thebore 41 ahead ofthe rear block 55. Thus, acetylene from the conduit I5 in the handle Aows forwardly through the passage I1 in thev head block II to theannular chamber 33; (Thence, -the acetylene continues forwardly throughthe eccentric passages 25 in` the nipple I8 till it reaches the annularchamber 38. From this point, the acetylene passes forwardly through thebore 15, into the passage 16, thence through the conduit 11 to the headH, through the cross passage 18 in the head, back' it issues'therefrom.A plurality of widely spaced y y I passage 56 crosses the narrow gap s.and enters radial projections 63 around the periphery of the mixingthroat 82, forming the rst section of the mixture conduit 5I, at a highvelocity. The

creates a vacuum in the narrow gap 6I. 'Ihis vacuum causes the acetyleneto flow forwardly through the elongated-annular chamber around ingelement 53 to the narrow gap 6I where'it moves inwardly at increasingvelocity until it.

meets the stream of oxygen on all sides thereof l The two gasesthereupon mix as they enter the mixing throat 82. `From the mixingthroat, the mixed gases pass into the second section of the mixtureconduit 5I, namely, an expansion passage 83 where theY velocity, of themixed' gases is reduced.

Thence the mixed gases pass through ia passage 84 in the head H`to aportion of the cavity 46 therein, whence they enter the usualcombustible mixture passages in the tip T in conventional element in theacetylene. line.

manner and are discharged from the blowpipe. The two gases thus increasetheir velocity immediately before they come in contact with one another,and meet at right angles to each-other.

The mixing action of the two gases is essentially independent of theacetylene pressure, as,

if the acetylene pressure is high, for instance, the needle valvecontrolling the flow of acetylene m'ay be manipulated to throttle thisflow and thereby maintain a fixed vacuum at the gap 6l regardless of theacetylene pressure. The value of the vacuum may be so chosen that theaspiration action of the oxygen on the acetylene will insure the correctgas mixture for the particular nozzle or tip T being used.

Should a backfire occur, it will first enter the mixture conduit 5|,which is formed of a metal having high heat conductivity and which hasexceedingly thick walls. The mixture conduit will therefore extract anddissipate much of the backfire heat quite rapidly. The danger that thispart may be damaged or burnt out is accord-4 ingly minimizedi` Next, thebackfire must pass through a, metering constriction in either gas line,such as the metering constriction B2 in the oxygen line, or the meteringconstriction provided by the gap 6I or the space surrounding the mixingThe cushioning effect of the large volumes of gas in each supply lineback of the mixing element tends to drive the backfire forwardly of theblowpipe again. Should a backfire pass either metering constriction, itwould be smothered in the largepassage behind that constriction withoutcontinuing to burn and become a flashback. Usually, because of therelatively low pressure of the acetylene as compared with that of theoxygen, the major portion of the backfiring gases passes .along theoutside of the mixer nozzle 53, which is spaced from the internal wallof the cavityrand from the rear end of the mixture conduit 5| to providea passage of sufficient size to permit the passage of backflres. Thisportion of the backfire then is extinguished in the large volume ofacetylene contained in the annularvchamber surrounding thecombustion-supporting gasconduit 54 and in the U-shaped passage formedby the conduits 11 and 19 and the header 1I. By the describedconstruction, therefore, a highly flashback-resistant blowpipe has beenprovided in which the distance between the rearL body member and theforward end of the blowpipe is maintained unusually short, so that theblowpipe may be attached'to an ordinary welding blowpipe handle withoutproducing a long and unwieldy assembly.

The large volume of acetylene contained in the space between theelongated conduit 5I and the inner wall of the elongated cavity whichsur- .rou'nds it,A and, back of that, in the U-shaped passagehavingterminals in the body formed by assures .a steady even 1. Ablowpipe comprising, in combination, a body member; a combustible gasmixture con# duit; means providing a cavity terminating at its rear endin said body member, and terminating at its forward end at the rear endof said mixture conduit; means at the forward end of said blowpipe fordischarging a combustible gas mixture; a mixer nozzle in said cavity,the external wall of said mixer nozzle being spaced from the internalwall of said cavity and from the rear end of said mixture conduit toprovide along the outside of said mixer nozzle a passage of suicientsize to permit the passage of backfires; means providing a generallyU-shaped fuel-gas passage'having an appreciable volume disposed betweensaid body member and the forward-end of said blowpipe, said fuel-gaspassage having a return bend at the front'thereof and having twoterminals at the rear thereof in said body member, said fuel-gas passagebeing adapted to contain a large volume of fuel gas for receiving andextinguishing backfires, therebypreventing flashbacks; means providing apassage communicating 'between one of said terminals and the passagealong the' outside oi.' said mixer nozzle; means for supplying fuel inggas conduit in said cavity spaced from thel l internal wall thereof toprovide an elongated'anconduits 11A and 19, so flow of acetylene ra allyinwardof the gap 6I regardless of conside le changes in acetylenepressure.A Since the mixing action of the mixing element hereindescribed, is not dependent` upon pressure, the blowpipe may be employedeili-` ciently over wide ran'gesof fuel gas pressure.

The form of the invention here described and illustrated in theaccompanying drawing is disclosed merely to indicate how the inventionmay be applied. Other forms differing in detail but not in principlefrom that here shown and described, will, of course, suggest themselvesto those skilled in the art.

We claim: f

4.ciable volume;

cured to the forward ed of said combustionnular chamber having anappreciable volume; a mixer nozzle in said cavity secured to the forward'end-*of said combustion-supporting gas con-v duit, said mixer nozzlebeing so constructed and arranged that` backfires will pass into saidannular chamber; means providing a generally U- shaped fuel-gasl passagehaving an appreciable volume disposed between said body member and the4forward end of said blowpipe, said fuel-gas passage having a returnbend at the front thereof and havingtwo terminalsat the rear' thereof insaid body member; means providing a passage in i said body membercommunicating between one of said terminals and said annular chamber; 1means for supplying fuel-gas to the other of saidv terminals and meansfor supplying combustionsupporting gas to said combustion-supporting gasconduit; said U-shaped fuel-gas passage and said annular chambercooperating to contain together a sufiiciently large volume of fuel gasto receive and extinguish backres passing said mixer nozzle, therebypreventing flashbacks.

3. A blowpipe comprising, combustible gas mixturejconduit; ahead memberat the forward end of said mixture conduit; a body member; cavity.terminating at its forward end at the rear end of said mixture conduit,and terminating at its rear end in said body member; an elongatedcombustion-supporting gas conduit in said cavity spaced from theinternal wall thereof to provide an elongated annular lchamber having anapprea mixer nozzle in said cavity sesupporting gas conduit, said mixernozzle being so constructed and .arranged that backfires will pass intosaid annular chamber: means providing in combination, a

means providing an elol'igated.

2,238,470 Y l l 5 a generali-y.- U-shaped Vfuel-gas passasehaving anappreciable volume comprising a header in said .headmemben and 'twoconduits, each conduit being in communication at its forward end withsaid header4 andterminatingat its rear end in said body member; meansproviding a passage in said body'member communicating between one ofsaid lastfnamed conduits and said annular cham- Hbei-:'.meansforsupplying fuel gas to theother` ofsaid last-named conduits; and meansfor :s'up- 10 l plyingcombustionfsupportins gas to said com`bustion-supporting gas'oonduit: said U-shaped fuel-gas passage and saidannular'chamber cooperating to containtogether a .sumciently large yvolume of fuel gas to receive and extinguish backres passing said mixernomic,4 thereby preventing flashbacks.

wnaor J. JAcoBssON.

Y normanna,v

